Check phrase codes, active intervals, prefix bits, and routes

Choose the operation contract or failure response implied by each structure. Verify outputs against a direct reference model.

Lessons

• LZ78 phrase tries: emit dictionary index and next symbol
• Segment-tree stabbing indexes: list intervals active at one point
• Huffman trees: assign prefix codes from symbol frequencies
• Condensation DAGs: compress directed cycles before path queries

Design exercise

• Project: audit phrase codes, active intervals, prefix bits, and routes
• Data Structures